Apparatus for lubricating moulds for blanks

Abstract

An apparatus for lubricating the internal wall of moulds for blanks comprises a corona charger for charging electrically the lubricant which is then injected into the mould. This latter is maintained at an electric potential such as to attract the lubricant and cause it to be deposited on the inside walls of the mould.

I claim: 
     
       1. In a press for compacting powdered material for sintered parts of high density, comprising a mould and at least one plunger adapted to be actuated by a cyclic shaft to effect a preliminary compacting, an electrodynamic unit for the high density compacting and including an apparatus for lubricating the mould comprising a reservoir for mixing the lubricant with dry air, a corona charger connected to said reservoir for charging electrostatically the mixture of said lubricant and dry air, a distributor connected to said corona charger actuatable for injecting said mixture into said mould, means operative to maintain the mould at an electric potential such as to attract the lubricant and cause it to be deposited on the inside walls of the mould, an element carried by the said shaft for actuating said injecting distributor in a predetermined time relationship with respect to said compactings, and a recycling blower connected between said distributor and said reservoir so as to keep said mixture in circulation. 
     
     
       2. An apparatus for lubricating a mould for blanks, comprising: a reservoir for mixing the lubricant with dry air,   a corona charger connected to said reservoir for charging electrostatically the mixture of said lubricant and dry air,   a distributor connected to said corona charger for injecting said mixture into said mould,   means operative to maintain the mould at an electric potential such as to attract the lubricant and cause it to be deposited on the inside walls of the mould, and   a recycling blower connected between said distributor and said reservoir so as to keep said mixture in circulation.   
     
     
       3. An apparatus for lubricating moulds for blanks comprising a reservoir for mixing dry air with the lubricant, a corona charger for electrically charging the mixture of air and lubricant, said reservoir being connected to the corona charger, injecting means for injecting said mixture of air and lubricant inside the mould, said injecting means including a distributor connected to said corona, a valve connected to the distributor and actuatable to control the injection of the mixture, means operative to maintain the mould at an electric potential such as to attract the lubricant and cause it to be deposited on the inside walls of the mould, a recycling blower connected between the distributor and the reservoir, and actuating means for actuating said valve so as to cause said blower to keep the dry air and lubricant mixture continuously in circulation when the valve is not actuated, while the mixture is injected into the mould when the valve is actuated. 
     
     
       4. An apparatus according to claim 3, for a powder compacting press including a mould filling shoe, wherein the distributor is provided with nozzles and is connected to the corona charger and to the recycling blower through flexibles pipes, the distributor being mounted on the mould filling shoe. 
     
     
       5. An apparatus according to claim 4, wherein said distributor is mounted on the shoe at the side of the feed duct for the powder, comprising oscillating means for giving to the filling shoe an oscillating movement for effecting the lubrication of the mould and the loading of the powder in sequence at the beginning of each compacting cycle. 
     
     
       6. An apparatus according to claim 5, wherein the oscillating means comprise a rotatable cam and cam following means, said cam being provided with two prominences connected by a portion of constant curvature, the first prominence causing the positioning of the nozzles in the loading opening of the mould and the second prominence causing the positioning of the feed duct for the powder in the loading opening of the mould. 
     
     
       7. An apparatus according to claim 6, wherein said actuating means comprise an electromagnet, and a generator for energizing said electromagnet to actuate the valve when the distributor nozzles are positioned in the loading opening of the mould, the generator being enabled to emit a square wave of predetermined length by a proximity sensor triggered by an element bodily rotatable with said cam. 
     
     
       8. Apparatus according to claim 7, wherein said element is positioned in a plane parallel to the plane of the cam so as to produce the opening of the valve when the distributor nozzles are positioned in the loading opening of the mould.